package spec.ganlijuan.unit4.animal;

public class MathTest {
    public static void main(String[] args){
        StringBuffer sb1 =new StringBuffer();
        System.out.println(sb1.length());
        sb1.append("ABC\n");
        System.out.println(sb1.length());
        sb1.insert(1,"F");
        System.out.println(sb1);

    }
}
